When holes opened up in the earth recently in Siberia, a wave of speculation was set off as to their cause. Scientists are now pinpointing a dramatic increase in arctic thawing, which may have released methane once trapped below the frozen ground. For a better understanding, Judy Woodruff talks to Tom Wagner of NASA.

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JUDY WOODRUFF:

Finally tonight, new indications that the planet is warming, especially in the frozen north. Scientists have been tracking Arctic thawing for decades, and they have seen a dramatic increase since 2000.

When holes opened up in the earth recently in Siberia, a wave of speculation was set off as to their cause. Scientists now think warming is the culprit.

To help us understand all this, we welcome back Tom Wagner. He directs studies of the polar regions for NASA.

And it's good to have you on the program again.

TOM WAGNER, NASA:

Thanks for having me back.

JUDY WOODRUFF:

So, just for those folks who don't follow the polar region so closely on a regular basis, like you do, remind us, what is the Arctic made out of and how are you seeing it change?

TOM WAGNER:

Yes, so the top of the Arctic is an ocean covered by sea ice, but all around it are the lands of Russia and Alaska and things. And that's frozen ground, ground like in your backyard, but it's frozen solid.

JUDY WOODRUFF:

And what have you been observing, you and other scientists, in terms of the change?

TOM WAGNER:

Well, in general, the Arctic has warming.

We know there's been less sea ice. We also know snow melts earlier and things like that. But this recent story from Siberia took everybody by surprise, because literally holes the size of a football field just opened up in the ground.

JUDY WOODRUFF:

And so scientists have taken a look at it. We have got some pictures to show people. What do they think is going on?

TOM WAGNER:

Yes, this is one case where the Internet has been amazing, because the scientific community has been talking about this.

Initially, people thought it was caused by methane had built up and caused a big burst out of the ground.

JUDY WOODRUFF:

Methane gas, which is — would have come from?

TOM WAGNER:

Right.

You can almost think of some parts of the Arctic as like a frozen swamp, where you have this decaying plant matter. That decaying plant matter releases methane. It can be stored in a couple of ways. But, as you thaw it, those gases get released. So, one of the initials questions was, had there been a big buildup of gas underground that caused an explosion?

JUDY WOODRUFF:

But, as time has gone by, you and other scientists have taken a closer look. And what are you now thinking?

TOM WAGNER:

Well, still, nobody has really visited the area, so no one knows, but more likely it's something akin to a sinkhole, like kind of what's has happened in Florida or what happens under a street when you get a water main break and it blows out a lot of the soil underneath and the street collapses.

JUDY WOODRUFF:

But why is it of concern? For those who are thinking about the Arctic, thinking about the health of the planet, the health of humans on the planet, why is this a worry?

TOM WAGNER:

So, nothing on this scale had been observed before. And this is an extremely cold part of the world.

So what we're saying is that, hey, this part that should have stayed frozen, it is melting and it's melting so fast, there's things going on that we haven't seen before.

JUDY WOODRUFF:

And what do you think is going on?

TOM WAGNER:

Well, probably what is happening is this, is by thawing of the permafrost, you're releasing water.

That water is carving out tunnels and caves under the permafrost. And we had probably a collapse and the water blew back out and brought out the material that you see erupted around the edges. But bigger what is going on is that frozen in this permafrost is a tremendous amount of carbon and methane, more than is stored in all of the living creatures and plants that the earth's surface today.

So the fear is that as this melts, that carbon and methane gets released into the atmosphere, and rapidly increases the rate at which the planet warms.

JUDY WOODRUFF:

And because it adds to the carbon levels that create warming all over the planet.

TOM WAGNER:

Exactly, more carbon dioxide in the atmosphere.

Also, methane itself is more powerful at warming the planet than CO2 is. I should say, too, there was just a big National Academy released calls Abrupt Climate Change that people should go look at. Fortunately, one of the things they concluded was that maybe we don't have to worry about a really rapid loss of methane from the Arctic in the next century, but it's speculative.

JUDY WOODRUFF:

So, for someone like you who looks at this, you had to believe that the methane was going to come out at some point. So, I guess I'm curious about, are you saying that it's now coming out faster than you thought it was going to be released into the atmosphere and that's why humans have to be worried?

TOM WAGNER:

Right. There are two different things going on.

One — and we actually fly airplanes and use satellites to look at how much methane is coming out of the Arctic now. And it's tough stuff to do, you know, because you're talking about a gas seeping out of the ground and, in some cases, coming out of the ocean.

But we know that that gas loss is intimately tied to the physical process of melting. And that's why these holes are important, is because they're saying, hey, even in these remote, cold corners, it looks like there's melting going on.

JUDY WOODRUFF:

Can you — does this improve the ability of scientists to measure the rate of global warming, the rate of climate change?

TOM WAGNER:

It gives us a better handle on what's happening in some parts of the Arctic that we didn't much about know before.

It's also pretty important, because what's happened is the sea ice from this Russian sector of the Arctic has receded a lot more than it has in other parts of the Arctic. And that is allowing heat from the ocean to get transferred on land. And all of this helps us understand the processes better of how the Arctic is changing.

JUDY WOODRUFF:

How much access, Tom Wagner, do scientists have to these sites, where the craters, these sinkholes are happening?

TOM WAGNER:

Oh, it's a tough question.

This is a really remote part of the world, and it's very, very difficult to get there. I was talking to some of the people that are — they work closely with the scientists who work there. And even for those scientists that get there, it's difficult to do. It's really remote.

JUDY WOODRUFF:

Does that matter? Can you still do the science if you're not actually there? We see a picture. Somebody's there, but you're saying for many people to get there…

TOM WAGNER:

Oh, it makes it really challenging.

And that's one of the things. The permafrost and the Arctic in general is this fantastic record of science and changes our planet went through in the past. But going and working there is profoundly difficult.

One of the things is, you can't even just — you can't drive across it because in the summer months, the surface layer melts, and it's impassable.

JUDY WOODRUFF:

So, if you're sitting here in the United States, and here in Washington, D.C., or Tampa, Florida, or Houston, Texas, or Los Angeles, California, do you worry about this? What are we to make of this?

TOM WAGNER:

What you should make about it this, is that we're starting to understand better how the Earth's system works.

And these holes are an example of just how the dynamic the Earth can be. But we're starting to get a better handle on the Earth's system. How is carbon being released into it, and how is that going to change the planet in the future?

But what we have to understand is the planet isn't just changing. It's changed, and we need to prepare for more of it.

JUDY WOODRUFF:

And what does that mean? What can people do?

TOM WAGNER:

Well, some changes are already happening. It's getting warmer in lots of parts of the world. Sea levels are already rising along coasts. And those things are going to continue.

There's also another great report called the National Climate Assessment which just came out. We also know precipitation patterns are going to change. There is going to be more flooding and more intense rainfall in some parts of the world. There are a lot of great resources out there to help everybody plan from kind of at the local level through to the federal level.

JUDY WOODRUFF:

So, another wakeup call.

TOM WAGNER:

Another wakeup call, but a really interesting one that I hope makes people just enjoy science too a little bit, mysterious holes in some part of the world.